Conventionally, there is known a chair which includes a seating body having a seating face, and a leg member for supporting the seating body, in which the seating body is placed on the leg member, and the seating body and the leg member are fixed with a screw (for example, see Patent Document 1).
In a chair of Patent Document 1, as shown in FIG. 2 or the like, a screw is inserted from a mounting portion 15 of a leg frame 6 (a leg member) to screw a supporting member 3 so that a film-like member 2, which has a seating face, is mounted to the leg frame 6.
In many cases, a portion in which a screw hole is formed has a boss shape that is thicker than its periphery. An example of the seating body formed as having a boss shape is shown in FIGS. 11A to 11C and FIGS. 12A to 12C. Each of FIG. 11A and FIG. 12A shows a back surface of a seating body 101, and each of FIG. 11B and FIG. 12B shows a cross sectional view on a screw hole. Each of FIG. 11C and FIG. 12C shows a schematic side view when fixed with a leg member (a metal claw 111) using a screw 35.
FIGS. 11A to 11C show a structure in which a boss 107 is formed only at a periphery of a screw hole 103. FIGS. 12A to 12C shows a structure in which a rib 109 is formed so as to surround a seating face 105 and a screw hole 103 is formed in the rib 109. A seating face 105 can be formed of various materials such as mesh (shown on the left side in FIGS. 11A and 11B and FIGS. 12A and 12B) and a resin plate (shown on the right side in FIGS. 11A and 11B and FIGS. 12A and 12B).